Metal gate electrodes are fabricated in metal oxide semiconductor (MOS) transistors in some advanced integrated circuits (ICs) to increase performance parameters such as on-state drive current. It is observed that p-channel metal-oxide-semiconductor (PMOS) transistors with metal gate electrodes may exhibit an increase in threshold voltages as the gate dielectric layer thicknesses decrease to ranges used in high performance complementary metal-oxide-semiconductor (CMOS) ICs, for example below 2 nanometers. Moreover, work functions of metal gates commonly do not match work functions in p-type polycrystalline silicon gate electrodes, leading to less performance than desired from metal gate PMOS transistors.